While the idea of accidentally hooking up with one's cousin is quite disturbing, it's a real possibility when you live in a place like Iceland that only has 300,000 people to choose from. That's why there's a new website called Íslendingabók, aka the Book of Icelanders. It sounds like a cooler version of Facebook, but it's actually a genealogy registry that keeps track of a whopping 1,200 years worth of people and tells you if you're related to someone. It sounds like a must-check before any first date—because the only thing worse than dating your cousin is having to dump your cousin. Oh, the site can also tell you if you're related to any celebrities, which basically means it can tell you if you're related to Bjork, since she's pretty much the only famous Icelander.